It is proposed to improve the in vitro conditions to achieve a faster rate of growth of cockroach embryo cell lines and to infect these cells with intracellular symbiotes removed from host insects. The objectives are to identify the extracellular factors which destroy the symbiotes, to observe the means of their penetration into new host cells, and to develop a milieu which favors their continued multiplication intracellularly. Attempts will be made to mimic an intracellular environment for the symbiotes. The effects of the culture conditions will be separated from the effects of the natural immune system of the host cells. The heat production of insects infected with either pathogenic or mutualistic microorganisms will be recorded in a microcalorimeter and compared to other bioassays. Efforts will be made to rear the aster leafhopper aseptically on the chemically defined diet, and to eliminate its symbiotes. BIBLIOGRAPHIC REFERENCES: Kurtti, T.J. and Marion A. Brooks. 1976. The dissociation of insect embryos for cell culture. In Vitro 12: 141-146. Brooks, Marion A. 1976. Applications of insect tissue culture to an elucidation of parasite transmission. In "Invertebrate Tissue Culture" (ed. K. Maramorosch). Academic Press, Inc., New York, pp. 181-199.